JPS62127785A - Mounting method for photosensitive drum - Google Patents

Abstract

PURPOSE:To prevent the occurrence of a scratch on a photosensitive body surface with the rolling off of a drum even when a load is applied to the drum with the bending of a paper due to the jamming of the paper in the vicinity of the drum by mounting a photosensitive drum with the freedom degree to a drum receiving part. CONSTITUTION:Bearing members 19 and 20 have a bearing at the central part, and a housing as a whole has the shape in which the surface along the direction to insert it toward bearing member holders 21 and 22 comes to be a plane. On the other hand, receiving parts 23 and 24 of the bearing receiving members 21 and 22 are formed in a U-shaped way approximately, and at the inside surface, a roller bearing 25 is provided. When the bearing member holders 21 and 22 are inserted into the receiving parts 23 and 24, both are engaged through the roller bearing 25, and the smooth shifting can be executed along the direction of the receiving parts 23 and 24. Thus, the photosensitive drum 1 is equipped with the degree of freedom along the inserting direction of the receiving parts 23 and 24 and the shifting of a rotary shaft center can be executed.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a method for mounting a photosensitive drum in a device using an optical semiconductor such as a copying machine or a laser printer. The present invention relates to a method for mounting a photosensitive drum that can prevent damage to a photosensitive member even if a paper jam occurs in a recording paper conveyance path, particularly in a portion such as a transfer section that is in contact with the photosensitive drum.

(Prior Art) Image formation using a copying machine or a laser printer is performed by sequentially processing a photoreceptor as a photosemiconductor through charging, exposure, development, transfer, and cleaning steps. When continuous image formation is performed, these series of processing steps are repeated.

Therefore, in order to speed up image creation and downsize devices such as copying machines, many devices use a cylindrical drum as a photoreceptor. This is because by arranging each processing process on the circumferential surface of the drum, it becomes possible to perform a series of image forming processes as the drum rotates.

Generally, the rotational movement of the photosensitive drum for performing each image forming process is performed by transmitting rotational driving force from a motor to the rotational shaft of the drum using rotational transmission means such as gears. In this case, if exposure unevenness or vibrations due to rotation occur during rotation, the image will be distorted and the image quality will deteriorate. Therefore, the rotating shaft of the angry light drum must be firmly mounted using a bearing etc. to prevent it from shaking completely. The current situation is that

When the rotating shaft is firmly attached in this way, smooth rotation without wobbling is achieved, but the disadvantage is that if a sudden load is applied to the drum due to a paper jam, the load force will cause scratches on the surface of the photoreceptor. will have the following.

Generally, in devices such as copying machines, as a countermeasure against paper jams, a microsinch or a photo sensor is used to detect a paper jam and stop the rotation of the drum to prevent damage to the drum.

Most of the detection uses microsinches installed at regular intervals to detect whether or not the recording paper is being conveyed accurately along the recording paper conveyance path from paper feed to paper ejection in chronological order. It is something. In this detection method, one microswitch detects the passage of paper, and if the next microswitch does not detect the passage of paper within a predetermined time, it is determined that a paper jam has occurred between the two switches. It is something. Based on this judgment, the rotation of the photosensitive drum is stopped. In devices that use this type of detection method, there is a slight lag time between when a paper jam actually occurs and when the photosensitive drum stops, and during this time the drum is rotating, which places a strong load on the drum. If it is added, there is still a disadvantage that there is a high risk of damaging the photosensitive drum.

(Object of the Invention) Therefore, an object of the present invention is to provide a method for mounting a photosensitive drum that does not damage the surface of the photosensitive drum even if a paper jam occurs in an apparatus that employs the general paper jam detection method as described above. It's about doing.

Another object of the present invention is to provide a method for mounting a photosensitive drum that can prevent damage to the drum during the period from a paper jam until the drum stops rotating while ensuring stable rotation.

(Structure of the Invention) In order to achieve the above object, the present invention provides a cylindrical photosensitive drum having a flange portion having a rotating shaft at both ends so that it can be mounted in contact with the recording paper conveyance path of the apparatus main body and its transfer portion. When the drum is rotatably mounted on a drum receiving section provided in shall be.

The present invention will be explained based on the following examples.

(Example) The present inventor deduces that damage to the photosensitive layer due to paper jam occurs for the following reasons. In other words, if recording paper is compressed and jammed at the transfer position in the conveyance path, a force will be generated that presses the paper against the drum surface. Unable to absorb power. As a result, it is inferred that if the surface hardness of the photosensitive layer is not sufficiently high, the photosensitive layer will be damaged by this pressing force.

Based on this reasoning, it has been found that such damage can be prevented if the photosensitive drum itself is provided with a mechanism capable of absorbing the above-mentioned pressing force. Therefore, the principle of the present invention is to employ a mechanism capable of displacing the center of rotation of the rotation shaft of the photosensitive drum in the mounting method of the photosensitive drum, and through the displacement, the photosensitive drum absorbs the pressing force generated due to jamming. That is what it is.

-1 body ■one Specific examples of the present invention will be described based on the following drawings.

(i) Photosensitive Drum The photosensitive drum mounting method of the present invention basically uses the photosensitive drum shown in an exploded perspective view in FIG.

The photosensitive drum 1 includes a cylindrical conductive substrate 5 having a photosensitive layer 3 on its surface, a flange 7.9, and a connecting member 11 that connects both flanges 7.9. Then, as shown in FIG. 3, the connecting member 11 and the flange 7.9 are screwed together with the screw member 13 so that the conductive substrate 5 is held between the flanges 7.9, thereby forming a drum unit.

The flange 7.9 used here has a protruding portion 15.16 whose center portion protrudes outward in the longitudinal direction of the photosensitive drum 1 in a cylindrical shape.
have. The protrusions 15 and 16 are then used as a rotation axis of the photosensitive drum. Moreover, one flange 9 is
Teeth 10 are formed all around the circumferential surface, and have the function of a single gear. This is this flange 9
This is for transmitting driving force from an external drive source to the gears via the drive gear 17 to rotate the photosensitive drum 1.

(ii) Attachment method To attach the photosensitive drum 1 to the main body of the apparatus, as shown in FIG.
9.20 is inserted into the bearing member receiver 21.22 attached to the side plate (not shown) of the main body of the apparatus. The bearing member receivers 21 and 22 house the bearing members 19 and 20, and when the photosensitive drum 1 is stationary at the bottom position, the photosensitive drum 1 is connected to the recording paper conveyance path (not shown) of the main body of the apparatus and its toner image transfer section. (not shown) is attached to the side plate of the main body so as to be regulated at an optimal position such that they come into contact with each other.

As described above, the present invention is characterized by employing a mechanism that displaces the rotational axis of the drum during this installation, and employs a mechanism that absorbs the pressing force generated by the paper jam. This mechanism will be explained below.

As shown in FIG. 1, the bearing member 19.20 has a bearing in the center, and the entire housing has a shape in which the surface along the direction of insertion into the bearing member receiver 21.22 is flat. One side bearing receiving member 21.2
The second receiving portions 23 and 24 are formed in a substantially U-shape, and a roller bearing 25 is provided on the inner surface. Then, the bearing member receiver 21.
22 is inserted, the two engage through the roller bearings 25, allowing smooth movement along the direction of the receiving portions 23 and 24.

(Thus, the photosensitive drum 1 is provided with a degree of freedom along the insertion direction of the receiving portions 23 and 24, and the rotational axis can be moved. Usually, the bearing members 21 and 22 are supported by the weight of the photosensitive drum. Smooth rotation is ensured around the protrusion 15.16 located at the bottom of the portion 23, 24 and whose position is regulated in this state. , the drum 1 can be displaced along the inner surface of the receiving part 23,24, thus making it possible to prevent damage.

In this case, the drive gear 17 needs to be engaged with the gear portion of the flange 9 at a position that does not restrict the displacement of the drum 1, and it is necessary to engage the drive gear 17 at a position below the horizontal plane that includes the rotation axis of the photosensitive drum 1. It is necessary to do so.

Moreover, it is most ideal that the direction of displacement of the bearing members 19, 20 is the vector direction of the pressing force caused by the paper jam. Since this vector direction differs depending on the positional relationship between the drum 1 and the paper conveyance path, it can be determined as appropriate by experiment depending on the apparatus. - For example, when the conveyance path is located in the tangential direction at the bottom of the photosensitive drum 1, it is preferable that the conveyance path be in the vertical direction or in an upward direction slightly inclined to the paper conveyance direction.

Note that when the engagement between the gear of the flange 9 and the drive gear 17 is released due to the displacement of the photosensitive drum 1, the rotation of the drum 1 will naturally stop, and the drum 1 will stop rotating due to paper jam detection.
If the rotation stop command signal is not issued, the stop caused by the release can serve as a kind of paper jam detection means.

After the photosensitive drum 1 is displaced due to a paper jam, the jammed paper may be removed and then the photosensitive drum 1 may be reinstalled in its normal position. However, in this example, if the jammed paper is removed, it can return to its normal position under its own weight.

In the present invention, a modification shown in FIG. 2 can be used. This modification improves the accuracy of the displacement response of the rotary shaft to the pressing force. This FIG. 2 is a schematic view showing only the relationship between the bearing member 19 and the bearing member receiver 21. As shown in FIG. The biggest feature of this modification is that
The self-weight of the photosensitive drum 1 is absorbed using the coil pin 31, and the coil pin 31 is made to act sensitively to the pressing force. That is, the hair ring member 19 is inserted into the bearing member receiver 21 similarly to the specific example shown in FIG. One end 32 of a coil spring 31 is fixed to this bearing member 19. The other end 33 of the coil spring 31 is hooked to the main body of the device in the same way as the bearing member receiver 21.

In this embodiment, the contractile force (restoring force) of the coil spring 31 acts between the main body of the apparatus and the photosensitive drum 1, and the dead weight of the drum 1 can be absorbed.

In this modification, if the pressing force for clogging is fl, the weight of the photosensitive drum is W, and the minimum force necessary to damage the Z optical drum is f2, then f2<W and f,>f.
It is valid when the following relationship holds true. That is, the gravity of the photosensitive drum 1 absorbed by the restoring force of the spring is
This is because if the spring constant is determined so that f2>W' in this case, the pressing force can be absorbed without being affected by the weight of the photosensitive drum.

This aspect is effective in an apparatus that employs a large and heavy drum.

Conversely, if the drum is very lightweight, W< f
If the relationship r < f z holds true, the drum 1 will be pushed up even though the pressing force is not a force that would cause damage.

In this case, the continuous rotation of the drum 1 will be hindered, so the spring 31 mentioned above is a compression coil spring, and the spring is adjusted so that the gravity W'' of the drum 1 with its biasing force becomes f2>W''. If a constant is determined and used, stable continuous rotation can be performed.

(Effects) According to the present invention, the photosensitive drum is mounted with a degree of freedom in the drum receiving portion, so even if a load is applied to the drum due to folding of paper due to a paper jam near the drum, etc. , the surface of the photoreceptor will not be scratched by the drum escape. Furthermore, if a jam occurs at the bottom of the photoconductor, that is, at the transfer section, the jammed paper can be simply pulled out and removed without damaging the surface of the photoconductor.

[Brief explanation of drawings]

FIG. 1 is an exploded perspective view for explaining the mounting state of the photosensitive drum, FIG. 2 is a diagram for explaining the drum receiving part, and
The figure is an exploded perspective view of the photosensitive drum. ■...Drum unit 5...Conductive base 7.9...Flange 19.20...Bearing member 21.22...Bearing member receiver 23.24...Receiving part

Claims (1)

[Claims] When a cylindrical photosensitive drum, which has flanges with rotating shafts at both ends, is rotatably mounted on a drum receiving part that is attached so as to be in contact with the recording paper conveyance path of the main body of the apparatus and its transfer part, A method for mounting a photosensitive drum, characterized in that the drum is mounted on a drum receiving portion so as to have a degree of freedom against pressure applied from the direction of a recording paper conveyance path.